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Flashcards in osteoporosis osteomalacia pagets Deck (29):
1

synthesized by osetoblasts, key regulator of phosphate homeostasis

FGF23

2

osteoclasts secrete ___ to disolve ____ and ____ to degrade bone matrix proteins

secrete HCl to dissolve mineral and cathepsin K to degrade bone matrix proteins 

2

oral bisphosphponates

 

side effects + contraindications

aalendronate

risedronate

esophogeal irritation

contraindicated for pt with GFR

3

osteomalacia = 

undermineralized bone matrix leads to weakened bone architecture

4

Antiabsorptives

Denosumab

Calcitonin

4

side effects calcitonin

tachyphylaxis - rapid loss of response to drug

nausea

4

Anabolic + mechanism

Teriparatide - fragement of parathyroid hormone, PTH stimulates bone remodeling

(continuous admin leads to bone loss)

5

in adution to promoting phophaturia, FGF23inhibits expression of ____ thereby ___-

 

it also increases activity of 24-hydroxlyase, increasing ___

inhibits expression of 1-hydroxylase, thereby reducing vitamin D activation

 

activity of 24-hyrdroxylase increasing vitamin D clearance

5

pathophys Autosomal dominant hypophopphatemic rickets 

 

X-linked and Autsomal recessive

AD = mitations in argiinate residues preventing normal proteolytic degradation of FGF23

 

X-linked - PhEX gene mutations prevent normal proteolytic degradation

 

AR = DMP1 mutations prevent degredation

7

interfaces between osteons

cement lines

7

selective estrogen receptor modulators for low BMD

 

mechanism

tamoxifen 

raloxifene

prevent increased remodeling 

8

PTH levels in osteomalacia

 

underlying mechanism

elevated, mineral diciency drives secondary hyperparathyroidism

9

pathophys Paget's disease

 

presentation

unregulated bone turnover > woven, increased intravascularity

 

headache

deafness (impingent)

limb bowing 

increased risk of osteosarcoma

10

IV bisphosphonates

 

side effects and contrandications

pamidronate

zoledronic acid

hypocalcemia,

acute phase rxn (flu-like symptoms)

contrainidicated for pt with GFR

11

tamoxifen side effects

 

alternate indications

increased thromboembolic risk

 

breast cancer adjunct

12

tumor induced osteomalacia pathophys and presentation

benign tumor of mesenchymal origin secreting large amounts of FGF23

 

serum phos falls and patients develop fatigue and proximal weakness

osteomalaic with detectable bone lonss on DXA

14

in osteomalacia, osteoid surface volume is 

increased

16

relative bone volume, cortical vs trabecular

80-90% cortical bone

17

inhibit converion of mevalonate to farnesyl, interfering with protein moification in osteoclasts, leading to apoptosis

Bisphosphonates

alendronate,

risedronate

panidronate

zoledrinc acid

18

osteopororsis = 

compromised bone strength due to bone densitiy and bone quaility that leads to increased risk of fracture 

19

pathophys of vitamin D resistant rickets

mutations of 1-hyroxylase encoded by CYP27B1 and

Vitamin D receptor encoded by VDR

20

signs of proper osteoblast activity in osteomalacia

elevated P1NP

elevated Alk Phos

21

people do not suffer from low bone mineral density unless 

fractures

22

Chronic negative Ca blance leads to _____ and if significantly prolonged, _____

secondary parathyroidism, if sufficiently prolonged, osteomalacia

24

accounts for 80% of bone turnover

trabecular

25

Denosumab mechanism 

 

side effects

decoy of receptor for RANK-L > prevents osteoclast differentiation

 

ONJm atypical femoral fractures

increase risk of skin infection

nauea, weakness, fatigue

26

___ and ___ are potent activators of osteoclast activity, providing free Ca and PO4

PTH

1,25diOHD

28

pseudofracture of femur common in ricketts

looser zone fracture

29

compressive strength comes from

 

tensile from 

compressive from mineral

tensile strength from protein (predominantly type 1 collagen)